RESUMEN
Objective To investigate characteristics of supraventricular tachycardia affiliated with rate-dependent concealed accessory pathway and the results of radiofrequency catheter ablation (RFCA). Methods Six patients (including 4 females and 2 males, agd from 14 to 68 years) had received electrophysiologic studies and RFCA, which included observing the properties of ventriculoatrial conduction while incremental pacing (S 1S 1) and single extrastimuli (S 1S 2) were performed in right ventricular apex (RVA) and left ventricle (LV), investigating the characteristics of tachycardia, mapping accessory pathway and evaluating the results from RFCA. Results There were 5 left free wall concealed accessory pathways and 1 right concealed accessory pathway at 11 o′clock of tricuspid valve in 6 patients. Five cases were confirmed with 1∶1 ventriculoatrial conduction through the concealed accessory pathway from RVA or LV pacing. The duration of the window ranged from 80 to 100 ms. Four cases were confirmed with accidental retrogradation through the concealed accessory pathway. The supraventricular tachycardia could be induced in 5 cases. All patients were successfully ablated from RVA pacing. Conclusion These results suggest that ventriculoatrial conduction would be rate-dependent because concealed accessory pathway takes place at phase block 3 or 4. In electrophysiologic studies we shoud carefully identify the accidental retrogradation through the concealed accessory pathway to avoid missed diagnosis.